The relationship between the subtropical ridge and Australian temperatures

Abstract

The intensity and latitude of the subtropical ridge over eastern Australia is strongly associated with southeast Australian rainfall, particularly during the cool months of the year. We show that the subtropical ridge also exerts a strong influence on temperatures across much of Australia, with warmer daytime temperatures and more warm extremes across southern Australia when the subtropical ridge is stronger than average, which is largely independent of the relationship between the subtropical ridge and rainfall. A strong subtropical ridge is also linked to warmer than average minimum temperatures over southern Australia throughout much of the year, except from May to August when a strong ridge is associated with cooler mean minimum temperatures and an increased frequency of cool nights. This relationship, and the observed strengthening of the subtropical ridge during autumn and winter in recent decades, can partially explain the weaker warming trends in minimum temperatures in southeast Australia compared to elsewhere in the country over the period 1960-2016.

An updated long‐term homogenized daily temperature data set for Australia

“…The updated ACORN‐SAT data will support ongoing analysis of temperature extremes in Australia, one example being the relatively weak trends in extreme low minimum temperatures in parts of southern Australia since the 1980s, associated with a strengthening of the subtropical ridge (Pepler et al ., 2018). The new data set will be supported by a comprehensive uncertainty assessment which is currently in preparation.…”

Weather and Climate Extreme Events in a Changing Climate

“…Yin and Sun (2018) found clear evidence of an anthropogenic signal in the changes in the number of frost and ice days, when multiple model simulations were used. In some key wheat-producing regions of Southern Australia, increases in frost days or frost season length have been reported (Dittus et al, 2014;Crimp et al, 2016); these changes are linked to decreases in rainfall, cloud-cover, and subtropical ridge strength, despite an overall increase in regional mean temperatures (Dittus et al, 2014;Pepler et al, 2018).…”

Can southern Australian rainfall decline be explained? A review of possible drivers

“…The intensified subtropical ridge has also been linked to increases in the frequency of high-pressure systems in southern Australia and the broader SH midlatitudes , contributing to drying trends. Trends during the summer months are less robust (Pepler et al, 2018;Timbal & Drosdowsky, 2013).…”